The present invention relates to a method and apparatus for tracing or following lines defining patterns on information-bearing media so as to "read" such patterns and provide usable input to an information processing system.
More particularly, the present invention relates to a method and apparatus which facilitates the automatic reading of two or three dimensional patterns, such as alpha-numeric characters, function curves and the like, which may be hand written, typed, printed or otherwise recorded on information-bearing media.
The purpose of such method and apparatus is to convert such patterns into signals which are readily usable as inputs to an information processing system.
Information-bearing media, of the type referred to above, may consist of "sheets" containing "line" information. It will be understood that such media are not limited to "sheets" in the common everyday sense of sheets of paper, since readable information may be rendered on the surface of any suitable structure. Furthermore, it is to be understood that a "line" may include or define a pattern such as an alphabetic or numeric character, a design or drawing of any arbitrary or familiar nature.
The art is replete with different types of apparatus, evolved over several decades, for reading and recognizing information, ranging from simple, template comparison devices to more recent sophisticated optical scanning systems for electronically converting written information into digital data that then may be transmitted, decoded, processed and reproduced. The present invention relates to devices in the latter category, although its principles of operation are not limited to "optical" scanning. The invention is equally applicable to the reading of magnetically recorded media as well as other information-bearing media on which the recorded information is not visible.
The present invention, however, is primarily concerned with a method and apparatus of the type that accepts and scans sheets of paper or other material which carry visible patterns located somewhere within a prescribed field of vision. The apparatus locates the patterns and produces a digital output for application to an information processing system such as a programmed general purpose digital computer or an "adaptive" information processing system.
Adaptive information processing systems have received significant interest over the years and a considerable amount of prior art has developed which includes the U.S. Pat. No. 3,287,649 to Rosenblatt, U.S. Pat. No. 3,408,627 to Kettler, U.S. Pat. No. 3,435,422 to Gerhardt et al, U.S. Pat. No. 3,533,072 to Clapper and the U.S. Pat. No. 3,601,811 to Yoshino. Of particular interest are the commonly-owned U.S. Pat. Nos. 3,950,733 and 4,044,243 to Cooper and Elbaum.
The Cooper and Elbaum patents disclose the so-called Nestor.TM. adaptive module which operates to map an input signal into an output response in accordance with a particular algorithm. When operating in a "learning mode" the Nestor adaptive module modifies itself to both "learn" and "forget" at desired rates. When operating in a "memory mode" the module neither learns nor forgets but functions as a pure distributed memory. The apparatus according to the present invention preprocesses signals which may be applied as inputs to such a module.
Various techniques have been used in the past for "reading" lines or patterns on an information-bearing sheet. The U.S. Pat. Nos. 3,603,931 to Britt, 3,303,465 to Essinger et al and 2,682,043 to Fitch disclose various techniques for detecting pattern information overlayed onto a grid. These references are typical of a large body of art which locates points on the grid on which a pattern is present either by direct "bit mapping" of all or a number of points on the grid simultaneously or by scanning the grid, line by line, in the manner of a television raster. None of these references discloses a device which is capable of directly reading or following a line or pattern in a progessive, orderly manner so as to provide information to an information processing system which may be recognized with a minimum of processing.